Clonidine, sold under the brand name Catapres among others, is an α2-adrenergic agonist medication used to treat high blood pressure, attention deficit hyperactivity disorder, drug withdrawal (alcohol, opioids, or nicotine), menopausal flushing, diarrhea, spasticity, and certain pain conditions. It is used by mouth, by injection, or as a skin patch.
An older antihypertensive that has come to be used in the treatment of childhood attention deficit-hyperactivity disorder. Structurally similar to the short-acting muscle relaxant tizanidine, clonidine is a centrally acting adrenergic agonist that decreases sympathetic activity. When used with opioids, clonidine can decrease the amount of opioid needed to obtain a high. Misuse of the drug has been associated with an increasing number of emergency department visits.
Clonidine is also structurally similar to the animal tranquilizer xylidine. When an increasing number of emergency department visits for overdose revealed xylidine in the patients’ blood.